Claims:

1. A system, comprising:a. a means for hermetic sealing of pixel element
electronics embodied within discrete flexible pixel elements, including
an encapsulation means and an external casement means; and,b. a
connection means for connecting power and signal cables conjoining a
plurality of discrete flexible pixel elements in series-connection,
wherein electrical conductors and terminal contacts embodied within said
power and signal cables are similarly protected.

[0004]This application is also related to U.S. utility patent application
entitled "Flexible Pixel Element and Signal Distribution Means" (Attorney
Docket DAKTRONICS P652), application number to be assigned, filed
concurrently herewith, a copy of which is attached and the disclosure of
which is incorporated by reference as if fully set forth herein.

[0007]Flexible pixel elements may be used in large scale, direct view
electronic display devices and signage mounted on large area and/or
irregular surfaces, such as the interior or exterior of buildings, where
the intent is to complement the surface architecture of the building by
conforming to the building surfaces. A particular problem arises with
electronic display devices used in outdoor or exterior displays such as
signs since delicate electronic components in such displays are exposed
to the detrimental effects of environment, rough handling and inclement
weather and are therefore vulnerable to failure. The discrete flexible
pixel element, fabrication method and means for hermetic sealing of the
present invention precludes failure of electronic components due to the
detrimental effects of environment, thereby enabling efficient,
economical production of large scale, direct view electronic display
devices, signage and lighting effects for outdoor use.

[0008]2. Description of the Prior Art

[0009]Electronic display devices and signage are known in the art. An
electronic display device typically comprises a display board that
produces visual images by means of a grid of small light emitting
elements, such as incandescent bulbs, LEDs, or the like; data handling
and control means for managing transfer of digital image data for display
as visual output images, and means for converting digital image data into
visual image data and display control signals to drive the light emitting
elements, or pixels, to thereby produce visual output images on the
electronic display devices for viewing.

[0010]The sophistication of visual images that can be displayed on
electronic display devices is generally dependent on the capabilities of
the light emitting elements, or pixels, used to produce visual images.
Light emitting display technology has become increasingly more advanced
in the art, progressing from monochrome incandescent and LED devices to
video quality components capable of exhibiting near continuous tone
visual output, complex animations and live video streams. Improvements in
light emitting display technology, including light emitting elements,
have in turn enabled the manufacture of electronic display devices that
are increasingly large in scale and more powerful in terms of the
complexity and sophistication of the visual output images that can be
displayed.

[0011]Electronic display devices and signage sited in outdoor locations,
such as on the exterior surfaces of buildings, are also known in the art.
Outdoor electronic display devices and signage are commonly sited near
public venues where the visual output images they exhibit may be viewed
simultaneously by large numbers of people in groups. Outdoor electronic
display devices provide a valuable service to the public since they can
provide timely or time-critical information, such as stock and commodity
prices, traffic and weather conditions, hazard alerts, and other
important information. One popular type of outdoor electronic display
device is a large scale video for advertising displays and signage where
commercial messages are broadly and effectively exhibited for public
viewing.

[0012]An inherent problem in the design and manufacture of large scale
electronic display devices for outdoor use is the need to protect
delicate and vulnerable internal electronic components from failure due
to the detrimental effects of environment. This problem is exacerbated by
the increasing sophistication of light emitting elements and their
collateral support electronics, such as the electronic drivers for the
light emitting elements. In the early art, incandescent bulbs served as
light emitting elements. Incandescent bulbs are comparatively inexpensive
to use, robust in operation and easy to replace; moreover, they require
few and comparatively inexpensive collateral support electronics and
power and signal conductors. More advanced light emitting elements or
pixels, such as LEDs and LCDs, are more expensive to use and replace. In
addition, they require more numerous and more expensive collateral
support electronics, including pixel element drivers, data buffers,
control signal handlers, over-voltage and transient protection circuits,
to name a few. Furthermore, advanced light emitting elements and
collateral support electronics are comparatively much more delicate and
easily damaged by electrostatic shock, thermal shock, mechanical shock,
moisture and humidity, and various other detrimental environmental
conditions. Advanced light emitting elements and collateral support
electronics also require more sophisticated means of mounting and
electrical connection, such as surface mounted printed circuit boards
(PCBs), as well as more sophisticated means of supplying operating power,
digital image data and display control signals, which means greatly
increase the number of signal paths and conductors needed to service
components and thereby greatly increase the number of connection points
and potential points of failure. Therefore, the use of advanced light
emitting elements, while presenting advantages in terms of the
sophistication of visual output images that can be displayed, also
presents a vulnerable design architecture with many potential points of
failure.

[0013]In the prior art, light emitting elements are collectively sealed
within enclosures to protect them from the outside environment. Not only
does this add to the cost of producing already expensive large scale
outdoor electronic displays and signage, but such enclosures are
generally effective only for conventional, rectilinear or planar displays
mounted on flat surfaces. Producing collective enclosures that conform to
irregular shaped surfaces can be a complex and costly undertaking.
Moreover, a collective enclosure typically embodies a single-point
failure mode, wherein any failure of the collective enclosure exposes all
the light emitting elements, collateral support electronics and
connection points contained therein to potential failure. Finally,
collective enclosures are subject to overheating from both internal and
external sources, including component power dissipation and solar
radiation.

[0014]A solution to some of these problems is taught in co-pending U.S.
utility patent application entitled "Flexible Pixel Element and Signal
Distribution Means" (Attorney Docket DAKTRONICS P652), application number
to be assigned, filed concurrently herewith, a copy of which is attached
and the disclosure of which is incorporated by reference as if fully set
forth herein. A portion of that teaching is the use of a plurality of
discrete flexible pixel elements that can be interchangeably connected in
series by means of flexible cables to produce flexible pixel strings that
are conformable to irregular shapes and surfaces.

[0015]The present invention further discloses means and methods that are
operative and efficacious in manufacturing discrete flexible pixel
elements, including a fabrication method and means for encapsulating
pixel element electronics, such as light emitting elements and collateral
support electronics, and encasing the encapsulated pixel element
electronics in an external top encasement cover in order to produce a
unitary, hermetically sealed, self-contained module that is protected
from the detrimental effects of the environment. The present invention
also discloses means for connecting power and signal cables to a
plurality of discrete flexible pixel elements in series connection,
whereby electrical conductors and contacts within power and signal cables
are similarly protected.

[0016]In summation, the prior art is generally dependent on conventional
means, such as collective enclosures, to protect pixel element
electronics used in electronic display devices sited outdoors from
preventable failure and damage. Conventional collective enclosures are
not well suited for protecting electronic display devices that conform to
irregular shapes and surfaces since they are difficult and expensive to
fabricate. Furthermore, they embody a single point failure mode which
exposes all internal components and connections to potential failure, as
well as being subject to overheating. As a result, production of such
enclosures is cost prohibitive, while outcomes are often inelegant and
failure prone. A novel approach to address the aforesaid deficiencies of
the prior art is needed to continue to satisfy public demand and thereby
ensure continuing development of the art.

SUMMARY OF THE INVENTION

[0017]The general purpose of the present invention is to protect delicate
and vulnerable pixel element electronics used in discrete flexible pixel
elements from failure and damage due to detrimental effects of
environment. More specifically, the present invention discloses a
fabrication method and means for hermetic sealing of pixel element
electronics embodied within discrete flexible pixel elements. The
fabrication method comprises an encapsulation means and an external
casement means. In addition, the fabrication method embodies connection
means for connecting power and signal cables conjoining a plurality of
discrete flexible pixel elements in series-connection, wherein electrical
conductors and terminal contacts embodied within said power and signal
cables are similarly protected.

[0018]The encapsulation means may include the use of a potting resin or
gel that encapsulates said pixel element electronics and hardens on
exposure to the atmosphere, heat, or a reactive agent such as a hardener.
Alternatively, the encapsulation means may include the use of a ductile
foam or malleable solid potting material having similar protective
properties in application and which harden by similar processes to
achieve similar results.

[0019]External casement means may embody a formed top encasement cover of
plastic or similar material, wherein the top encasement cover has an
internal cavity configured to receive encapsulated pixel element
electronics in assembly. The formed top encasement cover may be
transparent to pass light from light emitting elements or may have holes
therein enabling the light emitting elements to protrude therefrom in
order to pass light directly.

[0020]Alternatively, external casement means may embody a formed top
encasement cover which has an internal cavity configured to receive pixel
element electronics not yet encapsulated and which serves as a potting
shell enabling pixel element electronics positioned therein to be
encapsulated in situ.

[0021]In another alternative embodiment, external casement means may
embody a formed top encasement cover which is formed around encapsulated
pixel element electronics in a fused close fit therewith, such as by
plastic forming or by an injection molding means.

[0022]In yet another alternative embodiment, the formed top encasement
cover may have some corresponding fitting features adaptively to receive
a barrier sealant means which may embody a ductile barrier sealant such
as caulk or a malleable barrier sealant such as sealing lace or cord or a
solid barrier sealant such as a sealing gasket or O-ring, wherein said
corresponding fitting features engage the barrier sealant in a close fit
therewith to establish a sealed barrier to atmosphere.

[0023]Connection means for connecting power and signal cables conjoining a
plurality of discrete flexible pixel elements in series connection may
embody formed cable connectors of plastic or similar material that house
and mechanically support electrical conductors and terminal contacts,
wherein said formed cable connectors and terminal contacts have
corresponding fitting features which enable them to conjoin in a close
mechanical fit to thereby establish series connections between a
plurality of discrete flexible pixel elements, and wherein said close
mechanical fit establishes a sealed barrier to the atmosphere.

[0024]According to one embodiment of the present invention, there is
provided a fabrication method for hermetic sealing of pixel element
electronics embodied within discrete flexible pixel elements which
comprises an encapsulation means, an external casement means and a
connection means for connecting power and signal cables.

[0025]According to another embodiment of the present invention, there is
provided an encapsulation means that includes the use of a formed potting
shell which has fitting features for receiving a pixel element
electronics assembly, further presenting cavities for receiving potting
material, thereby enabling the encapsulation of said pixel element
electronics assembly through the introduction of the potting material,
and further having fitting features for receiving components of said
external casement means in a close fit therewith.

[0026]According to still another embodiment of the present invention,
there is provided a potting resin or gel that encapsulates a pixel
element electronics assembly which potting resin or gel hardens by
exposure to the atmosphere or heat or by a reactive agent such as a
hardener. The potting resin or gel is selected or formulated for optimal
performance characteristics and properties efficacious for encapsulating
pixel element electronics of discrete flexible pixel elements and
protecting them from the detrimental effects of the environment.

[0027]According to yet another embodiment of the present invention, there
is provided an external casement means which embodies a formed top
encasement cover and formed bottom plate of plastic or similar material,
wherein the formed top encasement cover has an internal cavity configured
to receive the encapsulated pixel element electronics assembly and which
further has fitting features to receive said formed bottom plate in close
fit therewith, the formed top encasement cover having through holes
therein to enable the light emitting elements to protrude therefrom.

[0028]According to still another embodiment of the present invention,
there is provided connection means for connecting power and signal cables
that embody formed connector headers of plastic or similar material which
house and mechanically support electrical conductors and terminal
contacts and which have fitting features enabling them to conjoin in a
close mechanical fit, thereby establishing a sealed barrier to the
environment.

[0029]A significant aspect and feature of the present invention is that
the fabrication means which enables the hermetic sealing of delicate and
vulnerable pixel element electronics contained within discrete flexible
pixel elements in order to protect them from failure and damage due to
the detrimental effects of the environment.

[0030]Another significant aspect and feature of the present invention is
that the hermetically sealed discrete flexible pixel elements can better
withstand the rough handling and mechanical shock during the shipping and
assembly of electronic display devices and during required service and
replacement thereof upon failure.

[0031]Yet another significant aspect and feature of the present invention
is that the hermetically sealed discrete flexible pixel elements can
better withstand inclement weather, moisture and humidity, electrostatic
shock, thermal shock, and other detrimental effects of the environment,
therefore they are better adapted for application in outdoor sites.

[0032]Still another significant aspect and feature of the present
invention is that the hermetically sealed cable connectors and conductors
supplying said pixel element electronics will protect the terminal
connections from possible failure and damage due to rough handling and
the detrimental effects of the environment.

[0033]A further significant aspect and feature of the present invention is
that the hermetically sealed flexible discrete pixel elements do not
require expensive collective enclosures thereby preventing individual
failure of discrete flexible pixel elements and pixel element electronics
embodied therein due to single-point failure of the enclosure.

[0034]A further significant aspect and feature of the present invention is
that the hermetically sealed discrete flexible pixel elements will ensure
greater longevity of pixel element electronics embodied therein and are
more easily replaced upon failure.

[0035]A final significant aspect and feature of the present invention is
that the fabrication method and means for hermetic sealing of discrete
flexible pixel elements provide a robust design architecture, an improved
cost-benefit in the design, manufacture and maintenance of large scale,
direct view electronic display devices and signage for outdoor
applications.

[0036]Having thus described embodiments of the present invention and
setting forth significant aspects and features of the present invention,
it is the principal object of the present invention to provide a discrete
flexible pixel element that is hermetically sealed from the environment
and embodied as a unitary, self-contained, replaceable module for
efficient, economical production of large scale, free-form electronic
displays, signs and lighting effects for outdoor applications. The
present invention teaches a fabrication method for producing hermetically
sealed discrete flexible pixel elements including means for encapsulating
pixel element electronics, exterior casement means, and cable connector
means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]Other objects of the present invention and many of the attendant
advantages of the present invention will be readily appreciated as the
same becomes better understood by reference to the following detailed
description when considered in connection with the accompanying drawings,
in which like reference numerals designate like parts throughout the
figures thereof and wherein:

[0039]FIG. 2 is a cross section side view of a pixel element electronics
assembly attached to a potting shell with fasteners;

[0040]FIGS. 3A and 3B are isometric top and bottom views of a pixel
element electronics assembly and potting shell in assembly with potting
material being applied to upper and lower cavities in the potting shell;

[0041]FIG. 4 is an isometric assembly view of a discrete flexible pixel
element showing a pixel element electronics assembly and potting shell in
assembly, top cover and bottom gasket;

[0043]FIG. 6A is a cross section side view of a plurality of discrete
flexible pixel elements of the present invention in series connection
with pixel element electronics assemblies therein fully encapsulated by
potting material and attached to a planar mounting surface;

[0044]FIG. 6B is similar to FIG. 6A but with the plurality of discrete
flexible pixel elements attached to a non-planar or irregular surface;
and,

[0046]FIG. 1 is an isometric view of a preferred embodiment of discrete
flexible pixel element 10 of the present invention. The flexible pixel
element 10 embodies a printed circuit board assembly (not shown) on which
various surface mounted electrical components are soldered or
mechanically fastened to conductor pads by operative electrical
connection including a plurality of light emitting elements 13, top
encasement cover 30, input connector 14, output connector 16, and
flexible cables 18 embodying in assembly a unitary, self-contained,
replaceable module. The light emitting elements 13, or pixels, are
illuminated when energized by on-board pixel element drivers (not shown)
to produce a visual output in the form of emitted light. In a preferred
embodiment, the light emitting elements 13 comprise a plurality of red,
green and blue (RGB) colored LEDs.

[0047]FIG. 2 is a cross section side view of potting assembly 20, a top
encasement cover 30, and a bottom gasket 32. Printed circuit board
assembly 11 supports a plurality of surface mounted pixel element
electronics 15, including light emitting elements 13 and pixel element
drivers 15a, in addition to other collateral support electronics, such as
resistors and capacitors (not shown), soldered or mechanically fastened
to conductor pads by operative electrical connection. The printed circuit
board assembly 11 is fastened to a potting shell 22 by mechanical
fasteners 29 of sufficient length for attaching said discrete flexible
pixel element 10 in finished assembly to a mounting surface or back-plate
36 (see FIGS. 6A and 6B) of an electronic display device. Potting shell
22 is a formed housing of plastic or similar material that presents an
upper cavity 24 and lower cavity 26 for receiving potting material. Upper
cavity 24 has an upper cavity wall 24a of sufficient height to enable
said potting material to fill the upper cavity 24 to a cavity limit
indicated by reference numeral 24b, thereby to fully cover a proximal
lower portion of light emitting elements 13. The electrical conductors
13a of the light emitting elements 13, as well as the pixel element
electronics 15, are completely encapsulated. However, the distal upper
portions of the light emitting elements 13 are not encapsulated thus
providing an unobstructed transmission of light from the flexible pixel
element 10.

[0048]A lower cavity wall 26a has a sufficient height to enable potting
material to fill the lower cavity 26 to a limit, indicated by reference
numeral 26b, which is sufficient to fully cover flexible cable headers
17, 19 and a proximal portion of flexible cables 18, thereby fully
encapsulating flexible cable headers 17, 19, as well as the underside of
the printed circuit board assembly 11 and further providing strain relief
to flexible cables 18.

[0049]FIGS. 3A and 3B are top and bottom isometric views of potting
assembly 20. A potting material 28 is applied in sufficient quantity
(partially shown) to fill the upper cavity 24 of potting shell 22 to the
upper limit of the interior cavity wall 24a without overflow and to fill
the lower cavity 26 of potting shell 22 to the upper limit of interior
cavity wall 26a without overflow. Potting material 28 may be any
conventional potting material, such as epoxy or polyurethane potting
compounds, having optimal performance characteristics and properties
efficacious for encapsulating pixel element electronics 15 of discrete
flexible pixel assembly 10, to-whit: [0050](1) potting material 28 is a
thermally, chemically and electrically inert material that, when
hardened, protects pixel element electronics 15 from moisture, humidity,
solar radiation, atmospheric pressure changes, vacuum, corrosive
chemicals, electrical shock, thermal shock, mechanical shock, and other
detrimental environmental effects; [0051](2) potting material 28 is a
viscous material with optimal flow properties for application in
predetermined quantities for filling upper cavity 24 and lower cavity 26
of potting shell 22, either by manual application or by machine
application, such as by a meter-mix-dispense (MMD) method, at optimal
speed without overflow; [0052](3) potting material 28 is a sublimating
material with optimal state change characteristics to enable rapid
hardening, either by self-sublimation through exposure to atmosphere or
by use of a hardening agent; [0053](4) potting material 28 is an adhesive
material with optimal adhesion characteristics to fully bond with
interior cavity walls 24a, 26a of potting shell 22 without requiring
separate adhesion means; [0054](5) potting material 28 is a
volumetrically stable material that exhibits minimum shrinkage after
hardening; [0055](6) potting material 28 is a thermally conductive
material with exothermic characteristics for transmitting heat generated
by pixel element electronics 15 to the environment at a rate sufficient
to prevent thermal overload; [0056](7) potting material 28 is a strong
material when hardened and exhibits optimal compressive strength to
enable mounting discrete flexible pixel assemblies by mechanical
fasteners 29 without damage; and, [0057](8) potting material 28 is a
temperature resistant material when hardened and exhibits insensitivity
to ambient temperature within an operating range optimal for use in
outdoor applications of discrete flexible pixel elements 10 in electronic
display devices.Once applied, potting material 28 is allowed to harden in
a state change sublimation by exposure to the atmosphere or through the
use of a hardening agent, thereby completing encapsulation of pixel
element electronics 15 within potting assembly 20.

[0058]Those skilled in the art will apprehend that the foregoing
performance characteristics and properties of potting material 28 for use
in discrete flexible pixel elements 10 involves various design choices
and tradeoffs in the selection of optimal characteristics thereof.
Accordingly, reference to the performance characteristics and properties
of potting material 28 shall not be considered limiting in scope of the
types and formulations of potting materials 28 that may efficaciously be
used with discrete flexible pixel elements 10.

[0059]FIG. 4 is an exploded isometric assembly view of a discrete flexible
pixel element 10 showing potting assembly 20, top encasement cover 30,
bottom gasket 32, and potting material 28 residing in the potting
assembly 20. Top encasement cover 30 is a formed housing of an optically
opaque plastic or similar material that has a cavity 30a of sufficient
volume to operatively to receive an upper portion of potting assembly 20
therein and presenting a ring recess 30b within top encasement cover 30
for receiving a corresponding ring protrusion 22a of potting shell 22
enabling top encasement cover 30 to engage and conjoin potting shell 22
mechanically by snapping into place therewith. The top surface of the top
encasement cover 30 also includes a plurality of holes 31a-31n for
accommodating the partial protrusion of the light emitting elements 13.

[0060]Bottom gasket 32 is a formed pliable gasket of plastic, rubber or
similar durable material that has a ring extension 32a corresponding to a
ring recess 34 formed by a recess 22b in potting shell 22 and a
corresponding recess 30c in top encasement cover 30 when mechanically
conjoined, as heretofore described. Bottom gasket 32 mechanically engages
ring recess 34 by inserting the ring extension 32a therein in order to
effect a closure between the top encasement cover 30 at recess 30c and
potting shell 22 at recess 22b.

[0061]Advantageously, top encasement cover 30 operatively engages with and
conjoins potting shell 22, and bottom gasket 32 operatively engages with
and conjoins both top encasement cover 30 and potting shell 22, by means
of a mechanical fit and reliance on tension and compression forces
without requiring the use of an adhesive or recourse to mechanical
fasteners during assembly, thus reducing the cost of manufacture and
further enabling recovery of the top encasement cover 30 and bottom
gasket 32 on failure or damage of pixel element electronics 15.

[0063]FIG. 6A is a cutaway assembly view of discrete flexible pixel
element 10 showing potting assembly 20, potting material 28, top
encasement cover 30, and bottom gasket 32 in final assembly embodying an
hermetically sealed, unitary, self-contained replaceable module. As
shown, a plurality of light emitting elements 13 protrudes through an
equal plurality of through-holes 31a-31n in the top encasement cover 30
to present an upper portion of said plurality of light emitting elements
13 to the exterior side of top encasement cover 30 permitting an
unobstructed transmission of light. Mechanical fasteners 29 may be
fixedly attached to a mounting surface or to a back plate 36 of an
electronic display device. Alternatively, mechanical fasteners 29 may be
conjoined to a detachable footing (not shown) that allows discrete
flexible pixel elements 10 to be positioned in a nonfixed condition.
Input connector 14 engages with and mechanically conjoins output
connector 16a of the previous series connected discrete flexible pixel
element 10a. Output connector 16 engages with and mechanically conjoins
input connector 14b of the next series connected discrete flexible pixel
element 10b.

[0064]FIG. 6B is a cutaway assembly view similar to FIG. 6A but with a
string of discrete flexible pixel elements 10 attached to a non-planar or
irregular mounting surface 36.

[0065]FIG. 7 is a cutaway assembly view of input connector 14 and output
connector 16 showing internal components and corresponding fitment
features enabling same to engage with and conjoin in closed mechanical
fitment thereby to establish a sealed barrier to the atmosphere. Input
connector shell 40 is a formed housing of plastic or similar electrically
nonconductive material that supports a plurality of captive input
terminal contacts 41a of flexible cable 18a. Similarly, output connector
shell 44 is a formed housing of plastic or similar electrically
nonconductive material that supports a plurality of captive output
terminal contacts 41b of flexible cable 18b. An input connector key 42a
mechanically engages with and conjoins a corresponding output connector
key 42b. An input connector protrusion 43a mechanically engages with and
conjoins a corresponding output connector recess 43b by snapping into
place. Input connector 14 with input terminal contacts 41a mechanically
engage with and conjoin output connector 16 with output terminal contacts
41b in operative electrical connection therewith. Potting material 28 is
applied to cavity 40a of input connector housing 40 to encapsulate and
seal flexible cable 18a and providing strain relief and potting material
is similarly applied to cavity 44a of output connector housing 44 for the
same purpose. Upon engagement and mechanical connection, the terminal
contacts 41a of input connector 14 engage with corresponding terminal
contacts 41b of output connector 16 in a close mechanical fit thereby
effecting an operative electrical connection between the input terminal
contacts 41a and output terminal contacts 41b and simultaneously
isolating them from the outside environment by virtue of the sealed
barrier to the atmosphere.

[0066]Various modifications can be made to the present invention without
departing from the apparent scope thereof.